1. Field of the Invention
The present invention relates to grinding tools (see DEFINITIONS section), more particularly to outdoor grinding tools (see DEFINITIONS section), and also more particularly to rotating disc assemblies (including a disc and bit sub-assembly(ies)) for grinding tools.
2. Description of the Related Art
Various types of stump grinders exist in the prior art. These machines typically include: a chassis; a motor; a stump grinding wheel; and teeth. The stump grinding wheel is mechanically connected to the chassis and motor so that the motor rotates the wheel about its central axis. The stump grinding teeth are mounted to the wheel at angular intervals about the central axis. The teeth are mounted either to: (i) the side surfaces of the wheel; or (ii) the peripheral edge of the wheel. A mounting mechanism is used to rigidly mechanically constrain each tooth to the wheel.
In some prior art stump grinder designs, a pocket clamps a tooth having a cutting bit to the wheel and a pair of bolts fixes the pocket to the wheel. In prior art stump grinder designs where the tooth is mounted around the peripheral edge of the wheel, an O-ring or similar type of fastening mechanism is used to fix the tooth to the mounting block which in turn may be brazed or otherwise affixed to the wheel. Regardless of the type of mounting mechanism used, it takes a bit of time and tools to detach a worn or broken tooth from a mounting mechanism, and replace it with a new tooth.
The cutting bit portions of the teeth are worn (or “degrade”) by coming into contact with the wood of the stump being ground. Also, the cutting bit portions may come into contact with foreign objects embedded in the wood, such as rock, nails, or other hard substances. The impact with these harder objects greatly increases the degradation of the cutting bits. Once the edge is worn beyond an acceptable limit, the tooth or teeth must be changed.
Traditionally, changing the teeth required the operator to use a drill or other tool to remove bolts that fasten a pocket to the wheel. The teeth, in turn, are clamped to the wheel by the pockets. This process is laborious and, with conventional teeth, the entire tooth has to be discarded and replaced with a new tooth. Thus, in addition, to the downtime associated with changing the teeth, the teeth themselves raise the expense associated with the grinding operation.
U.S. Pat. No. 5,555,652 (“Ashby”) discloses a land clearing apparatus that includes a rotating rasp used to shred trees, brush and debris. More specifically, rasp 20 includes drum 22, guard 26, removable impact structures 34 and adaptors 48. As shown in FIG. 2 of Ashby, the removable impact structures and respectively associated are located at regular angular intervals around the rotating drum.
U.S. Pat. No. 5,996,657 (“Riesselman”) discloses a stump cutter including a rotatable disk having multiple cutting tool holders. The cutting tool holders each have a cutting tool bit cantilevered therefrom to engage a stump brought into contact with the cutting tool. The cutting tool holder/bit sub-assemblies alternate in the angular direction with sub-assemblies that Riesselman refers to as non-cutting protectors. As shown in FIG. 1 of Riesselman, each bit extend in the radial direction beyond the outermost radial edge of the protectors by a distance of L1. With respect to its protectors and bits Riesselman discloses the following: “In the embodiment shown, the protector 20 is spaced sufficiently far out so that cutting tool bites into an object only to the depth L1 of the hardened cutting tip 16. With traditional stump cutters, no leading protector is provided and the cutter wheel could inadvertently overbite and cause wheel hang-up. I have found that with use of a protector with a massive non-cutting leading edge which is placed ahead of the lead cutting tool a distance denoted by P1, the problem of broken cutting tools is substantially eliminated. That is, the non-cutting leading edge of the protector can be spaced rotationally ahead of the cutting tool to provide protection to the cutting tool. I have found that even with P1 distances of six or seven inches I can still provide protection for the first stage cutter and holder located behind the protector . . . . By having a massive protector that has a greater mass than the cutting tool and is not cantilevered outward as the cutting tool is, the protector can absorb shocks and impacts through gradual abrasion of the protector while the first stage cutting teeth of a row of cutting teeth can be protected.” Riesselman does not seem to disclose how large its dimension L1 is supposed to be.
U.S. Pat. No. 6,138,725 (“Leonardi 1”) discloses various operating angles and/or angles between components associated with a stump grinding tool rotating disc.
U.S. Pat. No. 6,176,445 (“Shinn”) discloses a cutter tooth located on the outer peripheral surface of a rotatable cutter adapted for clearing, mulching and grinding trees.
Other published documents which may be of interest include: (i) U.S. Pat. No. 5,743,314 (“Puch”); (ii) U.S. Pat. No. 7,484,541 (“Green”); and (iii) US patent application 2008/0149224 (“Kappel”).
Description Of the Related Art Section Disclaimer: To the extent that specific publications are discussed above in this Description of the Related Art Section, these discussions should not be taken as an admission that the discussed publications (for example, published patents) are prior art for patent law purposes. For example, some or all of the discussed publications may not be sufficiently early in time, may not reflect subject matter developed early enough in time and/or may not be sufficiently enabling so as to amount to prior art for patent law purposes. To the extent that specific publications are discussed above in this Description of the Related Art Section, they are all hereby incorporated by reference into this document in their respective entirety(ies).